// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_BIND_H_
#define BASE_BIND_H_

#include "base/bind_internal.h"

// -----------------------------------------------------------------------------
// Usage documentation
// -----------------------------------------------------------------------------
//
// See //docs/callback.md for documentation.
//
//
// -----------------------------------------------------------------------------
// Implementation notes
// -----------------------------------------------------------------------------
//
// If you're reading the implementation, before proceeding further, you should
// read the top comment of base/bind_internal.h for a definition of common
// terms and concepts.

namespace base {

// Bind as OnceCallback.
template <typename Functor, typename... Args>
inline OnceCallback<MakeUnboundRunType<Functor, Args...>>
BindOnce(Functor&& functor, Args&&... args)
{
    using BindState = internal::MakeBindStateType<Functor, Args...>;
    using UnboundRunType = MakeUnboundRunType<Functor, Args...>;
    using Invoker = internal::Invoker<BindState, UnboundRunType>;
    using CallbackType = OnceCallback<UnboundRunType>;

    // Store the invoke func into PolymorphicInvoke before casting it to
    // InvokeFuncStorage, so that we can ensure its type matches to
    // PolymorphicInvoke, to which CallbackType will cast back.
    using PolymorphicInvoke = typename CallbackType::PolymorphicInvoke;
    PolymorphicInvoke invoke_func = &Invoker::RunOnce;

    using InvokeFuncStorage = internal::BindStateBase::InvokeFuncStorage;
    return CallbackType(new BindState(
        reinterpret_cast<InvokeFuncStorage>(invoke_func),
        std::forward<Functor>(functor),
        std::forward<Args>(args)...));
}

// Bind as RepeatingCallback.
template <typename Functor, typename... Args>
inline RepeatingCallback<MakeUnboundRunType<Functor, Args...>>
BindRepeating(Functor&& functor, Args&&... args)
{
    using BindState = internal::MakeBindStateType<Functor, Args...>;
    using UnboundRunType = MakeUnboundRunType<Functor, Args...>;
    using Invoker = internal::Invoker<BindState, UnboundRunType>;
    using CallbackType = RepeatingCallback<UnboundRunType>;

    // Store the invoke func into PolymorphicInvoke before casting it to
    // InvokeFuncStorage, so that we can ensure its type matches to
    // PolymorphicInvoke, to which CallbackType will cast back.
    using PolymorphicInvoke = typename CallbackType::PolymorphicInvoke;
    PolymorphicInvoke invoke_func = &Invoker::Run;

    using InvokeFuncStorage = internal::BindStateBase::InvokeFuncStorage;
    return CallbackType(new BindState(
        reinterpret_cast<InvokeFuncStorage>(invoke_func),
        std::forward<Functor>(functor),
        std::forward<Args>(args)...));
}

// Unannotated Bind.
// TODO(tzik): Deprecate this and migrate to OnceCallback and
// RepeatingCallback, once they get ready.
template <typename Functor, typename... Args>
inline Callback<MakeUnboundRunType<Functor, Args...>>
Bind(Functor&& functor, Args&&... args)
{
    return BindRepeating(std::forward<Functor>(functor),
        std::forward<Args>(args)...);
}

} // namespace base

#endif // BASE_BIND_H_
